In core drilling operations, it is often desired to obtain a core sample to obtain geological information on a particular site. This operation is to be ideally accomplished without removing the drill string from the borehole. For this purpose, hollow drill strings have been developed and include a bit end at the end of the drill string and a core barrel unit positioned proximate the coring bit end. The inner tube assembly unit can be transported through the drill string and thus ideally avoid having to remove the complete drill string to obtain a core sample.
However, various drilling applications require the provision of a drilling apparatus where the drill string can be positioned in different orientations. This difference in positioning of the drill string imposes changes to the core barrel components to position the inner tube assembly properly and efficiently to the bit end of the drill string. Changing these core barrel components requires the removal of the entire drill string to gain access to them. This process can be very time consuming and is non-productive. Other drilling situations, such as in an underground mine, require the ability to drill in all orientations. Furthermore, in a down-hole application, the angle of the hole may be deviated to a flatter, horizontal angle, which would require a change to an up-hole configuration of the core barrel to efficiently propel the inner tube assembly to the bit end of the drill string. There is also a need to avoid reconfiguring core barrel outer tube components between surface and pump in/underground configurations.
U.S. Pat. No. 4,834,198 discloses a core barrel apparatus including an inner tube assembly that may fall under gravity or be fluidly propelled to a bit end of a drill string. The seal in this apparatus is interposed between lock nuts threaded on a latch body and a washer. The washer rests against a coil spring urging against a lower tubular member. The seal in such a configuration cannot be removed without affecting the proper interfacing of the remaining components.
U.S. Pat. No. 6,425,449 discloses a drilling apparatus including seals that are mounted on a latch body adaptor component that can be removed to convert from an up-hole to a down-hole configuration.
Consequently, there is still presently a need for a head assembly that is quickly reconfigurable between surface and pump in/underground configurations, easily maintainable on the field and requiring a minimal amount of parts to accomplish the reconfiguration.